Chambers, who has made four starts for Saints' First Team so far this season, captained the Young Lions in their previous game, a 6-1 friendly win in Estonia earlier this month.
Meanwhile, Targett – who was named in the First Team squad for last night's Capital One Cup win over Bristol City – has chosen to switch allegiances to England having previously represented Scotland at under-19 level.
Noel Blake's side will travel to Slovenia for their first qualifying matches, taking on the host nation as well as Andorra and Switzerland over a five-day period next month.
The top two sides will then progress into the elite round of qualifiers, which take place next spring and will determine the eight sides who progress to next summer's finals in Hungary.
Those who qualify for the 2014 UEFA European U19 Championship will also be given a place at the 2015 FIFA U20 World Cup, which will be held in New Zealand in two summers' time.